Security device and intrusion-alarm system

Abstract

A security device for an intrusion-alarm system, which comprises: radio-frequency detection means ( 10 ); means ( 11 ) for generating a signal indicating a possible sabotage, when the radio-frequency detection means detect a radio frequency over a defined time; means ( 12 ) for detecting an intrusion-indicating condition; means ( 13 ) for generating an intrusion-indicating signal when the means for detecting an intrusion-indicating condition detect an intrusion-indicating condition; and means ( 14 ) for generating an alarm-raising signal, in the event that the signal indicating a possible sabotage and the intrusion-indicating signal are generated. The invention also relates to an intrusion-alarm system which comprises such a device.

What is claimed is  
     
         1 . A security device for an intrusion alarm system, which comprises: 
 a radio frequency detector; a first signal generator which acts on a signal from the radio frequency detector for generating a first signal when the radio frequency detector detects a radio frequency for a time period greater than a defined time period;    a second detector capable of detecting an intrusion indicating condition; a second signal generator which acts on a signal from the second detector for generating an intrusion indicating signal;    a third alarm raising signal generator which is operated upon the first signal generator generating a first signal and the second signal generator generating an intrusion indicating signal.    
     
     
         2 . The security device of  claim 1 , wherein the radio frequency detector is configured to detect a signal frequency at which security devices typically transmit information related to detected intrusions.  
     
     
         3 . The device of  claim 2 , wherein the radio frequency detector is configured to detect a signal with a frequency of 433.92 MHz.  
     
     
         4 . The security device of  claim 1 , wherein the second detector for detecting an intrusion indicating condition comprises a vibrations detector.  
     
     
         5 . The security device of  claim 1 , wherein the third alarm raising signal generator and the second intrusion indicating signal generator are arranged such that an alarm raising signal is generated when the radio frequency detector detects a radio frequency for a period of time greater than the defined time period, and the intrusion indicating condition detector detects an intrusion condition and the detected radio frequency and the intrusion condition coincide in time.  
     
     
         6 . The security device of  claim 1 , wherein the third alarm raising signal generator and the second signal generator are arranged so that the third alarm raising signal generator generates a signal and the second signal generator generates a signal such that the third alarm raising signal is generated when the radio frequency detector detects a radio frequency for longer than a defined time and generates a first signal, and the second signal generator generates a second signal and the first and second signals are both produced within a defined period of time.  
     
     
         7 . The device of  claim 1 , further comprising a logic circuit with outputs at which defined signal levels are defined; the first signal generator, the second signal generator and the third signal generator are connected with the logic circuit; and the first signal, the intrusion indicating signal and the alarm raising signal correspond to defined signal levels at outputs from logic components of the logic circuit.  
     
     
         8 . An intrusion alarm system including a security device according to  claim 1;   the alarm system further comprising: 
 at least one intrusion detector peripheral which includes a third detector for detecting a second intrusion indicating condition and a transmitter for sending a coded signal to a central base by radio frequency when the second intrusion indicating condition is detected;  
 a central base comprising a signal receiver adapted to receive the coded signal by radio frequency when the second intrusion indicating condition is detected by the third detector and the coded signal is sent to the base;  
 a fourth alarm raising signal generator being operable by a received coded signal at the central base.  
   
     
     
         9 . The intrusion alarm system of  claim 8 , further comprising an alarm device and wherein the fourth alarm raising signal generator of the alarm system is adapted to transmit an alarm raising signal to the alarm device which generates an alarm.  
     
     
         10 . The intrusion alarm system of  claim 9 , wherein the alarm device comprises at least one of an independently powered siren and a telephone dialer for dialing a telephone number.  
     
     
         11 . The intrusion alarm system of  claim 10 , wherein the third alarm raising signal generator of the security device is adapted to transmit an alarm raising signal to at least one of a telephone dialer, and an independently powered siren, or to dial a programmed telephone number.  
     
     
         12 . The intrusion alarm system of  claim 8 , wherein the third alarm raising signal generator of the security device is adapted to transmit an alarm raising signal to at least one of a telephone dialer, and an independently powered siren, or to dial a programmed telephone number.  
     
     
         13 . The security alarm system of  claim 8 , wherein the radio frequency detector is adapted to detect a signal with a standard frequency used to communicate between the at least one intrusion detector peripheral and the central base.